Fulton–Lazarsfeld's connectivity conjecture for symmetric degeneracy loci

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Let XX be a smooth, projective, connected complex variety of dimension nn, let EE be a vector bundle of rank ee on XX, and let LL be a line bundle. Suppose that EE has an LL-valued quadratic form, that is, a section of S2E∗⊗LS^2E^*\otimes L. For an integer kk, let Dk(E)D_k(E) be the subscheme of XX where this section has rank at most kk, and set

t(e−k)=(e−k)(e−k+1)2.t(e-k)=\frac{(e-k)(e-k+1)}{2}.

Fulton–Lazarsfeld's connectivity conjecture. If

dim⁡Dk(E)=ρ:=n−t(e−k)≥1\dim D_k(E)=\rho:=n-t(e-k)\geq 1

and S2E∗⊗LS^2E^*\otimes L is ample, then Dk(E)D_k(E) is connected.

This is a conjecture attributed to Fulton and Lazarsfeld concerning the connectivity of degeneracy loci of quadratic forms; the supplied source does not state whether it has been resolved.

References

Primary source

Pierre-Emmanuel Chaput, “Théorèmes d'annulation et lieux de dégénérescence en petit corang”, arXiv:math/0502131 (2005).

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